Use of Deo's Classification System on Rock: Final Report

Report No: 83-R22

Published in 1983

About the report:

A shale from a construction site on Route 23 in Wise County, Virginia, was classified using Deo's classification system, and the usefulness of the classification system was evaluated. In addition, rock that had previously been used in the development of an acid soak test was re-sampled for use in determining the lowest percentage of concentrated sulfuric acid that would rapidly break down the Millboro type shale. It was concluded that the Deo classification system would be more effective and useful for working with the ostensibly tough Virginia shales if the tests were run for five cycles and if the physical condition of the tested particles of shale, as determined by observation, was given more weight than the numerical indices as an indicator of the long-term durability of the shale. It was recommended that the following methodology be adopted by the Virginia Department of Highways and Transportation for identifying Millboro type shales, which are physically tough but will weather in a relatively short time in a wet oxidizing environment. a. Note the color of the shale. b. If it is dark (green, gray) then look for iron sulfides. c. If these are present, then examine the shale for the clay mineral "chlorite". d. If chlorite is present, then the shale should be considered as having great potential for relatively rapid weathering and should not be used as rock. Also, it was recommended that black shales should be considered to be nondurable.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.


Other Authors

David F. Noble

Last updated: January 18, 2024

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